Personal computer systems are well known in the art. Personal computer systems in general, and IBM Personal Computers in particular, have attained wide-spread use for providing computer power to many segments of today's modern society. Personal computers can typically be defined as a desktop, floor standing, or portable microcomputer that is comprised of a system unit having a single central processing unit (CPU) and associated volatile and non-volatile memory, including all RAM and BIOS ROM, a system monitor, a keyboard, one or more flexible diskette drives, a fixed disk storage drive (also known as a "hard drive"), a so-called "mouse" pointing device, and an optional printer. One of the distinguishing characteristics of these systems is the use of a motherboard or system planar to electrically connect these components together. These systems are designed primarily to give independent computing power to a single user and are inexpensively priced for purchase by individuals or small businesses. Examples of such personal computer systems are IBM's PERSONAL COMPUTER AT and IBM's PERSONAL SYSTEM/1 (IBM (PS/1).
Personal computer systems are typically used to run software to perform such diverse activities as word processing, manipulation of data via spread-sheets, collection and relation of data in databases, displays of graphics, design of electrical or mechanical systems using system-design software, etc.
IBM PS/1s and PS/2s are desktop computers designed to be used at a single location. For example, in today's society many individuals have desktop computers at their desks or in rooms dedicated to computer-aided tasks. Desktop computers are typically set up at a location and used by one or many users without ever moving the computer.
Desktop systems may be classified into networked and non-networked computer systems. Networked computer systems are part of a larger computer system and are connected to other computers or servers via local area networks (LANs) or wide area networks (WANs). Such networks, using special interfaces and protocols, allow computers to share data and programs in an efficient way. Desktop computer systems used in businesses are typically networked computer systems. Non-networked computers, on the other hand, are not connected to any other computers. Data transfer from one computer to another is accomplished by writing data to flexible diskettes with a computer in one location and reading the data with a computer at another location. Desktop computers used in homes are typically non-networked computers.
Unlike desktop computers, which are designed to remain at a single site, portable computers, also known as "laptop computers" or "notebook computers" depending on their size, such as IBM's PS/2 L40 Think Pad, are designed to be taken with the user and used at any number of sites. For example, a salesperson might use a notebook computer at the salesperson's desk to generate a report on projected sales. If the salesman is called from the salesperson's desk to a meeting, the salesperson could suspend the current task, pick up the notebook computer, and take it to the meeting. Once at the meeting, the salesperson could take out the computer, resume the software execution, and take notes or call up information during the meeting. As another example, a student might be writing a term paper at home until class-time, at which time the student could take the notebook computer to class to take notes.
Portable computers are typically non-networked computers, although some users will connect their portable computers to an office LAN when the computer is to be used in the office.
Portable computers differ from desktop computers in a number of respects. Portable computers are typically powered by rechargeable batteries. The user will charge the batteries using electricity from a wall-plug, use the computer until the batteries need recharging, and then recharge the batteries. While the batteries are recharging, the portable computer may not be moved; the computer movement is limited by the length of the power cord. Thus, a computer having its batteries charged in effect loses its portability until the batteries are sufficiently charged. Like a flashlight, or other battery-powered device, the more power the portable computer consumes, the shorter period of time the user will be able to use the portable computer before the batteries need recharging. Thus, power consumption is a factor users consider when purchasing a portable computer and, not surprisingly, a major issue in the portable computer industry. Therefore, the computer industry has spent much time and money designing portable computers that use less and less electrical power.
However, there is a trade off; the low-powered computers use more expensive low-power components, which cannot execute computer commands as quickly as the faster, high-power components. Moreover, in addition to making use of more expensive components, portable systems typically use more complex designs, thereby adding to the cost of portable computer systems.
Desktop computers, by comparison, are usually powered using electricity from a wall-plug; desktop computers have no batteries to run low (with the exception of a very small battery used to back up the real time clock, which can last for years without recharging). Consequently, desktop computers may make use of the faster, high-power, and less expensive components. In short, the portable computers use less electrical power and are typically not as computationally powerful as desktop computers, which use more electrical power.
In today's energy-conscious society, simple alternatives exist to leaving desktop computer powered on all day. One alternative is a technology found in portable computers. If a portable computer is idle for a certain period of time, usually a number of minutes, the computer will automatically stop spinning the fixed disk within the fixed disk storage unit and stop generating the computer's display. Both of these acts conserve power.
Portable computers also have other more complicated ways of conserving battery-power. If the system is idle for a given period of time, some portable computer designs start turning components off in such a way that they may be restored with no data loss. To keep the memory from being lost, the portable computer has a special battery circuit to keep the power to the memory without power to the CPU and the other circuitry. The special battery circuit increases the cost and complexity of the printed circuit board and increases the number of components of the system. Another way to implement the suspend/resume function is to use a CPU that is a member of a special family of processors called the "SL" family. SL CPUs are designed differently and have special commands to allow designers to easily implement battery-power saving functions. However, the SL family is more expensive and processors from the SL family are typically not as computationally powerful as the standard processors. In addition, portable systems typically have expensive "shadow" registers to save the several write-only registers found in typical computer systems. Such special features add complexity and cost to the printed circuit board design and increase the number of components in the computer system. Moreover, it is generally believed that it is impossible to save the state of a non-SL 80386 or 80486.
Because of the many differences between portable computers and desktop computers, consumers expect laptop and notebook computers to be priced higher than desktop computers. Consumers expect desktop computers to be very computationally powerful, yet very inexpensive. Thus, a desktop computer implementing a suspend/resume scheme using the expensive and complex techniques used in portable computers would be too expensive to sell in the desktop market. Therefore, any power conservation implementations in desktop designs typically make use of existing components or make use of newer components that are at least as powerful as standard components used in desktop systems.
Moreover, networked and non-networked desktop systems have different requirements. Some LAN protocols require LAN hardware in a computer system to remain powered or the network might fail. Non-networked desktop systems obviously have no LAN hardware, so LAN failure is not a problem with non-networked systems.
It is, therefore, believed desirable to provide a desktop computer system with power management features similar or superior to portable systems.
It is also believed desirable to provide desktop systems with power management capability without using the more complex designs and expensive components used in portable computer systems with similar features.
It is also believed desirable to save the state of a non-SL 80386 or 80486 without using the more complex designs and expensive components used in portable computer systems with similar features.
The EPA has promulgated guidelines for energy-efficient computers. The EPA set EPA Energy Star requirements for computer systems desiring to be considered "Green," that is, energy efficient . A computer may be labeled with the "EPA Energy Star" label if it has a mode in which it consumes less than thirty watts of power, or the monitor consumes less than thirty watts of power, or if both the computer and the monitor each consume less than thirty watts of power. The EPA "Memorandums of Understanding" with individual manufacturers set out the power requirements. Desktop computers typically are not designed with these capabilities.
It is therefore desirable to provide a desktop computer that meets the "green" standard.
It is also desirable to take into account whether a computer system is a networked or a non-networked desktop computer in fashioning an energy-conservation system.
When computers are turned on, they typically go through a "booting" process. When a computer "boots" it first performs a power-on self-test (POST), which involves running various tests to ensure that the computer is functioning correctly. After performing the POST, the computer typically loads the operating system (OS), such as IBM's PC-DOS. After the OS is loaded, many computers load a graphic user interface (GUI), such as Microsoft's Windows. Then, the user must open application software and load working files. This entire process can take quite a bit of time--up to several minutes in some cases.
Although several minutes does not seem like much time, to a user waiting for a computer system to boot, load the OS, load the GUI, and load the applications, that time is unproductive and annoying and effectively prevents users from conserving power by making it very inconvenient to save power by turning off their computers. That is, such usability penalties make manual power management schemes impractical.
It is therefore desirable to provide a desktop computer system with power management capabilities without significant usability penalties. That is, it is desirable to provide a computer system that has a power-conservation mode and can later be resumed in an acceptable amount of time and in any event less than the amount of time it would take to restart the computer system.
Occasionally, a user might leave the desktop computer idle while an application is executing on the computer. For example, if the user is using a word processing program and a spreadsheet program simultaneously to prepare a sales report and the phone rings or the user is called away from the desk, the computer would still be executing the applications. Any effective power management implementation should be able to conserve power and at the same time prevent the user from losing data, which would occur if, for example, the computer powered itself off in the middle of an application. Moreover, current software applications do not automatically save their states in such a way that they may be resumed where they were interrupted.
It is, therefore, desirable to provide a computer system that can enter a power-conservation mode while applications are executing on the system. It is further desirable to make such a power conservation mode transparent to the application software.
Sometimes a user of a desktop computer might know if the computer will not be needed for a while. It is desirable to allow the user to be able to cause the computer to enter a power-conserving mode manually to save the power the computer would use while deciding that it has been idle long enough to warrant entering a power-saving mode.
It is, therefore, desirable to allow the user to manually cause the desktop computer to enter a power conservation mode, without first having to exit applications, and be able to resume using the applications as though the computer was not turned off.
Typical portable computers have a switch to control the power to the computer and a different switch to implement the suspend/resume function. This can cause user confusion and increases the cost and complexity of portable computers. Thus, it is desirable to provide a desktop computer system with the above power-conservation capability without using a plurality of buttons.